Field of the Invention
The present invention relates to an improvement in a safety seat-belt retractor for use in vehicles, and more particularly to an improvement in a safety seat-belt retractor including an elongated energy-absorption member which is forcedly drawn by and wound around a winding shaft to absorb a shock energy acting on a passenger upon occurrence of a predetermined deceleration of a vehicle such as upon the collision thereof.
A conventional safety seat-belt retractor of the kind described above, as is disclosed in Japanese Utility Model Laid-Open No. 100218/75, comprises a fixed frame, a winding shaft rotatably mounted on the frame, and a toothed member mounted on the winding shaft for relative rotation thereto. A seat-belt to be fitted on a passenger has one end secured to the shaft and is partly wound threaround. An elongated energy-absorption member has one end thereof secured to the shaft and the other end secured to the toothed member. The elongated energy-absorption member extends along a part of the outer circumferential surface of the shaft, is turned back and extends in roll around the shaft. Locking means comprising a pawl is operative in response to a predetermined deceleration of a vehicle, such as upon the collision thereof, to engage with the toothed member to lock the same against rotation relative to the fixed frame. When the toothed member is locked by the pawl, a tension on the seat-belt by a passenger causes the shaft to rotate relative to the toothed member so that the elongated energy-absorption member is forcedly drawn by and wound around the shaft to absorb a tension on the seat-belt, and hence a shock on the passenger.
However, in the arrangement of the conventional retractor discussed above, the radius with which the elongated energy-absorption member is turned back varies as it is wound around the shaft and is unstable. Thus, the energy absorbed by the elongated energy-absorption member, i.e., the tension on the seat-belt does also vary and fluctuate during the energy-absorption member is forcedly drawn by and wound around the shaft, and the varying shock energy acts on the passenger.